Device for deblocking lenses

ABSTRACT

A device for deblocking lenses attached to a block has at least one securing device supporting a lens and having an opening for a block suspended from the lens. At least one holding-down device is provided for pressing the lens supported on the securing device against the securing device. At least one impacting device with a striking member movable from below against the securing device for striking the securing device is provided. The securing device and the holding-down device are supported to be movable against a spring-elastic restoring force in a striking direction of the striking member.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a device for deblocking optical glasses(lenses), in particular, spectacle lenses, which are fastened on ablock, respectively. The device comprises at least one securing deviceon which a lens is supported and which has an opening for the blocksuspended from the lens. The device comprises at least one holding-downdevice for pressing the lens supported on the securing device againstthe securing device.

[0003] 2. Description of the Related Art

[0004] When manufacturing lenses of the aforementioned kind, the concavesides, inter alia, must be machined, for example, by milling, grinding,or polishing. The lenses to be processed are fastened by means of alow-melting alloy, whose melting point is approximately 55° C., on aso-called block. After completion of the individual processing steps,the lenses must be detached from the block. This separation of lens andblock is commonly referred to as deblocking. This is carried outpresently by hand. The lens fastened on the block projects laterallypast the block. For deblocking by hand, a piece of tube is employed andthe block is positioned in the tube opening. The diameter of the tube isof such a size that the lens, which radially projects relative to theblock, will rest on the rim of the opening of the tube. The upright tubeis then struck on a hard surface so that, as a result of the impactimpulse, lens and block will separate. The block then falls through thetube downwardly, while the lens remains in the hand of the operator.This manual deblocking process is cumbersome and monotonous labor.

[0005] Austrian patent 407 967 already discloses a device for automaticdeblocking. In this device, a carriage or slide, on which at least oneholder for a lens with a block connected thereto is provided, is movablealong a guide. The guide is part of a frame which is supported on astand to be moveable in the vertical direction. For receiving theoptical glasses (lenses) together with the blocks fastened thereto, theframe is lowered relative to the stand, the holders being open duringthis procedure. After closing the holders, the frame is again lifted andthe carriage or slide is moved along the guide provided on the frame tothe separating station. The frame is then lowered at great speed so thatthe jaws of the holder strike a plate of the separating station, and theacceleration force acting on the block now separates block and lens.

[0006] A disadvantage of this known device is that, for lowering theframe at great speed in order to realize deblocking, specialpiston-cylinder units for moving the frame must be employed which musthave special venting valves in order to be able to reach the requiredhigh speed. This leads to increased manufacturing costs. Also, a changeof the impact speed of the holder on the plate of the separating stationis possible only with complex modifications. For this purpose, thepiston-cylinder units have to be exchanged or the venting valves have tobe modified such that a changed venting action can be achieved. The useof an electric motor drive for adjusting the frame (instead of thepiston-cylinder unit) would require a relatively great manufacturingexpenditure. Moreover, in this known configuration the mass to be movedfor the deblocking process is relatively great so that high accelerationforces must be exerted causing great forces to be absorbed by thebearings.

[0007] A device for manual deblocking is also known from U.S. Pat. No.3,091,062. The block is inserted into an upright standard so thatminimal play relative to the standard remains. At the upper end of thereceiving standard a ring is arranged which is pivotable relative to thestandard by means of a lever and projects past the upper edge of thestandard on which lens is supported. By pivoting the ring in the upwarddirection, the lens is removed from the block. The block, as a result ofthe exerted tilting force, is canted relative to the standard so that noadditional securing device is required for the block. The one-sidedforce application onto the lens with this type of deblocking deviceresults in a relatively great risk of breakage of the lens. Also, anautomated operation of the device of U.S. Pat. No. 3,091,062 is nottaught and, moreover, would not be possible with a device of the thiskind.

SUMMARY OF THE INVENTION

[0008] It is an object of the present invention to provide an improveddevice of the aforementioned kind which can be produced lessexpensively.

[0009] In accordance with the present invention, this is achieved inthat at least one striking device is provided which has a strikingmember movable from below against the securing device for striking thesecuring device, wherein the securing device and the holding-down deviceare movably supported against a spring-elastic restoring force in thedirection of the impact or striking movement of the striking member.

[0010] In the device according to the invention, the masses which are tobe moved upon deblocking can be reduced, and the device can bemanufactured in a simpler way. Moreover, the deblocking process can beperformed more reliably wherein the number of rejects in the form oflenses damaged by deblocking is reduced.

[0011] In an advantageous embodiment of the invention, the securingdevice in the area of the support of the lens is of a sleeve-shapedconfiguration wherein the block suspended from the lens is arrangedwithin this sleeve-shaped area at a spacing to its inner wall. In thisway, a simple securing device is provided wherein a deblocking deviceaccording to the invention can comprise several such securing deviceswith different diameters and/or the securing devices can be adjusted forreceiving different sizes of lenses or blocks or they can beexchangeable.

[0012] It is expedient to provide the securing device with an anvil orsupport on a lower side opposite the lens resting on the securingdevice. The anvil should preferably be arranged centrally underneath thelens or the block suspended therefrom. This anvil or support serves forreceiving the impact exerted by the striking member so that the impactacceleration detaching the lens from the block is transmitted via theanvil onto the securing device.

BRIEF DESCRIPTION OF THE DRAWING

[0013] In the drawing:

[0014]FIG. 1 is a side view of the device according to the invention;

[0015]FIG. 2 is a plan view of the device according to the invention;

[0016]FIG. 3 shows a section along the line A-A of FIG. 1 (theholding-down device and the striking device are not illustrated insection);

[0017]FIG. 4 shows a lens attached to a block in a side view (enlargedscale);

[0018]FIG. 5 shows the lens on the block in a top view (enlarged scale);and

[0019]FIG. 6 shows a bottom view of the lens on the block (enlargedscale).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020]FIGS. 4 through 6 illustrate in different views the object to bemanipulated by the deblocking device of the present intention. On ametal block 1, which in this illustrated embodiment has a conicalportion 2 and a cylindrical portion 3 and is provided with a depression4 arranged centrally and open in the downward direction, is fastened bymeans of a low-melting alloy 5 to the spectacle lens 6 to be processedwhose concave side is to be machined. The block 1 can have differentshapes and different sizes depending on the type of the optical glass(lens) to be treated. The aforementioned block 1 with the easilymeltable alloy 5 is an auxiliary device with which the lens 6 to beprocessed is adjustable and positionable relative to the individualtools. The connection between the lens 6 and the easily meltable alloy 5is of satisfactory or sufficient strength so that the reaction powercaused by the tools when processing the lens can be transmitted safelyand reliably onto the block 1 inserted into a machine tool. Aftercompletion of processing of the lens 6, the lens and the block must beseparated. The device described in the following is provided for thispurpose.

[0021] In the illustrated embodiment several securing devices 8 forblocked lenses 6 are provided on a carriage 7. Two rows of five securingdevices 8 are provided. The carriage 7 is supported to be movable alongguide rails 10 by means of glide shoes 9. The guide rails 10 arefastened on a machine frame 11. For moving the slide or carriage 7, atoothed belt 12 is provided on which the carriage 7 is secured by meansof a holding part 13. The toothed belt 12 is of a continuous or closedconfiguration and runs on one side about a deflection roller 14rotatably supported on the machine frame 11. The other side is providedwith a drive roller (not visible in the illustration) driven by anactuator. In this way, the respective securing device 8 can be moved inan automated and program-controlled way into the required position inwhich deblocking of the lens 6 resting on the securing device is carriedout.

[0022] Moreover, a loading station can be provided, which is notillustrated in the drawing, for supplying the securing devices 8 withthe blocked lenses. In this connection, the carriage 7 can also bepositioned by program control in order to load the respective securingdevice. In place of an electric actuator for the carriage 7, it ispossible to provide a pneumatic adjusting devices instead.

[0023] For pressing an optical glass or lens 6 to be deblocked againstthe securing device, a holding-down device 15 is provided. In theillustrated embodiment, the holding-down device 15 is secured on apiston rod 16 of a pneumatic piston-cylinder unit 17 having a piston 18acting via both ends. In the activate state of the holding-down device15, air pressure loading the piston is present in the cylinder chamber19. When a force is exerted onto the piston 18 which acts against thisair pressure and is greater than the air pressure, the piston 18 ismoved by reducing the cylinder chamber 19 against this air pressure sothat the air pressure is increased. In this way, a kind of(pre-tensioned) air spring is formed against whose spring-elasticrestoring force the holding-down device 15 can be moved when acorrespondingly great force is exerted. In place of such an air springdevice, or in addition thereto, a pressure spring could be provided, forexample, between an adjusting device of the holding-down device 15 andthe holding-down device 15; the holding-down device 15 can then be movedagainst the spring-elastic restoring force of this pressure spring.

[0024] The securing devices 8 are sleeve-shaped at their upper areafacing the support of the lens 6. An inner sleeve part 20 is providedwhich is connected with an outer sleeve part 21. A plastic sleeve 22 isarranged between the inner and the outer sleeve parts 20, 21. O-rings23, 24 are arranged on the upper end faces of the inner sleeve part 20and of the plastic sleeve 22. The lens 6 is supported on the O-ring 23.The holding-down device 15 rests on the lens 6 and optionally on theouter O-ring 24. The block 1 suspended from the lens 6 projects throughthe opening 45 of the securing device 8 into the interior of thesleeve-shaped area of the securing device 8 and is spaced relative tothe inner wall 25 of the inner sleeve part 20.

[0025] The sleeve-shaped upper area of the securing device 8 is closedoff in the downward direction by a slantedly extending guide surface 26.This guide surface 26 opens into an ejection opening 27 for thedeblocked block 1. The block 1 which has been deblocked from the lens 6falls onto the guide surface 26 and then glides along it through theejection opening 27 into a guide tube 28 which opens into a receptacle(not illustrated in the drawing) for the blocks 1.

[0026] The securing device 8 is axially slidably arranged in a glidesleeve 29 relative to the glide sleeve. The glide sleeve 29 is arrangedin a support sleeve 31 which is connected to the frame of the slide orcarriage 7. A coupling nut 32 is threaded onto the lower end of thesupport sleeve 31 and forces an elastic ring 33 against the lower endface of the support sleeve 31. The elastic ring 33 projects inwardlysomewhat past the support sleeve 31, and the glide sleeve 29 rests onthe elastic ring 33 in this area. The support sleeve 31 and the glidesleeve 29 are flush with one another at their upper ends, and on theupper end faces of these sleeves a damping ring 34 is positioned. In thelower end position of the securing device 8, a shoulder 30 of thesecuring device, where the diameter is reduced, rests on the dampingring 34. At the location where the shaft 35 of the securing device 8projects downwardly from the coupling nut 32, an elastic rubber ring 36is secured on the shaft 35 and surrounds it in a circular ring shape.This elastic rubber ring 36 provides a spring-elastic element againstwhose spring-elastically acting restoring force the securing device 8can be moved upwardly in the axial direction by a small stroke. A bolt37, secured in the support sleeve 31 and projecting into a correspondingrecess in the area of the shoulder 30 of the securing device 8, providesa securing action against relative rotation.

[0027] On the lower end of the shaft 35 an anvil or support 38 isarranged and connected to the shaft 35. It is positioned centrallyunderneath the lens 6 or its block 1 suspended therefrom.

[0028] A device according to the invention comprises moreover a strikingdevice 39 which comprises a striking member 40 in the form of a type ofa hammer. The striking member 40 is secured on the piston rod 41 of apiston-cylinder unit 42 and, in its inactive rest (initial) positionbefore carrying out a strike, is positioned at a spacing from thesecuring device 8 or its anvil 38. By loading the piston-cylinder unit42, the striking member 40 is accelerated from below in the directiontoward the securing device 8 and carries out a strike onto the securingdevice 8 when impacting the anvil 38. By means of this impact, anacceleration is exerted onto the securing device 8 wherein the shaft 35is moved relative to the glide sleeve 29 with compression of the elasticrubber ring 36 in the direction 46 of the impact movement. Moreover, theholding-down device 15 is also moved in the upward direction by theupwardly moved securing device 8. The acceleration exerted onto thesecuring device 8 is transmitted onto the lens 6 so that the block 1 asa result of its inertia becomes detached from the lens 6. After theimpact energy has been received by the spring-elastic bearing devices ofthe securing device 8 and of the holding-down device 15, the devices 8and 15 return into their lower end position. In this connection, thesecuring device 8 is damped by the damping ring 34. The O-rings 23, 24are provided for an additional gentle treatment of the lens 6.

[0029] When attaching a lens on a block, an outwardly projecting nose 43(compare FIG. 6) can be produced on a peripheral location. In order toensure a proper deblocking action despite of this nose, a slot 44 may beprovided on the inner sleeve part 20 which extends in the axialdirection across the length of the sleeve part 20. When loading thesecuring device 8, care must be taken that a nose 43 which may bepresent is positioned above this slot so that this nose 43 can movethrough this slot 44 when the block 1 drops. In the case that anautomated loading device is provided, the lens which is gripped by alens holder could be rotated, for securing the correct angular positionof the nose 43, about a central longitudinal axis extending through thelens and the block until the nose of the block 1 rests against a stopwhich will position the nose properly.

[0030] Different modifications and alterations of the illustratedembodiment are conceivable and possible without leaving the realm of theinvention. For example, the support of the securing device that ismovable relative to a spring-elastic restoring force could also berealized in a different way then the one illustrated. For example, theshaft 35 of the securing device could also be attached to a bearingblock on an elastic material which, in turn, is fastened on the frame ofthe carriage. The movement of the securing device 8 would then berealized against the elasticity of the material of the bearing block.Also, the bearing device 8, in place of the sleeve-shaped area on whichthe lens to be deblocking is supported, could have a support which isadjustable with regard to its diameter in order to be able to deblocklenses or blocks of different diameters with one and the same securingdevice. A securing device could be provided in the area of the supportof the lens with several jaws surrounding a receiving opening for theblock and positioned at a spacing from one another in thecircumferential direction, wherein the diameter of the receiving openingis adjustable by scissor-type members, as disclosed already in the priorart deblocking device described supra.

[0031] In principle, it would also be conceivable and possible toeliminate the slide or carriage 7. The securing devices 8 would thus bestationary relative to the machine frame 11. In this situation, eachsecuring device 8 would be provided with its own holding-down device 15and its own striking device 39. Loading of one or several securingdevices could be carried out by hand.

[0032] While specific embodiments of the invention have been shown anddescribed in detail to illustrate the inventive principles, it will beunderstood that the invention may be embodied otherwise withoutdeparting from such principles.

What is claimed is:
 1. A device for deblocking optical glasses attachedto a block, the device comprising: at least one securing deviceconfigured to support an optical glass and having an opening for a blocksuspended from the optical glass; at least one holding-down device forpressing the optical glass supported on the securing device against thesecuring device; at least one impacting device comprising a strikingmember movable from below against the securing device for striking thesecuring device; wherein the securing device and the holding-down deviceare supported to be movable against a spring-elastic restoring force ina striking direction of the striking member.
 2. The device according toclaim 1, wherein the securing device has a sleeve-shaped upper areafacing the optical glass supported thereon and configured such that theblock suspended from the optical glass projects into an interior of thissleeve-shaped upper area and has a spacing to an inner wall of thesleeve-shaped upper area.
 3. The device according to claim 2, whereinthe securing device comprises a guide surface located underneath thesleeve-shaped upper area and extending downwardly, wherein the securingdevice has an ejection opening for the block separated from the opticalglass and wherein the guide surface opens into the ejection opening. 4.The device according to claim 1, wherein the securing device has a lowerside opposite the optical glass supported thereon and the lower sidecomprises an anvil for receiving a strike exerted by the strikingmember.
 5. The device according to claim 4, wherein the anvil isarranged centrally underneath the lens or the block suspended therefrom.6. The device according to claim 4, wherein the striking member has aninitial position before carrying out a strike and is positioned in theinitial position at a spacing from the anvil of the securing device. 7.The device according to claim 1, further comprising: a glide sleeve,wherein the securing device is supported in the glide sleeve and ismovable relative to the glide sleeve; and a spring-elastic elementconfigured to exert a restoring force upon movement of the securingdevice away from a lower end position.
 8. The device according to claim7, wherein the spring-elastic element is an elastic rubber ring fastenedon the securing device and resting against an underside of the glidesleeve or a part that is connected to the glide sleeve.
 9. The deviceaccording to claim 1, wherein the striking member has an initialposition before carrying out a strike and is positioned in the initialposition at a spacing from the securing device.
 10. The device accordingto claim 1, wherein the striking device comprises a piston-cylinder unitand wherein the striking member is attached to a piston rod of thepiston-cylinder unit.
 11. The device according to claim 1, comprising apneumatic piston-cylinder unit, wherein the holding-down device isfastened on a piston rod of the piston-cylinder unit.
 12. The deviceaccording to claim 1, further comprising a moveable slide, whereinseveral of the securing devices are arranged on the slide, wherein thesecuring devices are moveable alternatingly into a position opposite thestriking device.
 13. The device according to claim the 12, furthercomprising an actuator for a program-controlled automated movement ofthe slide.
 14. The device according to claim 1, wherein the opticalglasses are spectacle lenses.